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Monoclonal Antibodies for Cancer

Reviewed by Laura J. Martin, MD on June 14, 2020

Scientists create monoclonal antibodies (mAbs) in a lab. But these drugs work much like the natural antibodies your body makes to fight illness. After they're injected into your body, they help identify or attack problems like bacteria, viruses, and cancer cells.

Some monoclonal antibodies attack cancer cells directly. And some get at them indirectly, through other cells that help cancer spread. There are two main types:

Naked mAbs

These mAbs are called "naked" because they work by themselves, without having radiation or other drugs attached to them. They can kill cancer cells several ways:

  • Some mark cancer cells so your immune system can more easily spot them. For example, a mAb called alemtuzumab (Campath) attaches to blood cancer (leukemia) cells. This triggers your immune system to seek out and destroy them.
  • Other naked mAbs attach to cell parts that help cancer spread. Trastuzumab (Herceptin), for instance, blocks the work of the HER2 protein. HER2 helps breast and stomach cancer cells grow.
  • "Checkpoint inhibitor" mAbs stop your body from mistakenly marking cancer cells as safe. For example, ipilimumab (Yervoy) attaches to a protein that acts as a "hall pass" for some skin cancer cells. Once this mAb does its work, the hall pass is gone. Your immune system can now attack those cancer cells.

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Conjugated mAbs

To make conjugated mAbs, sometimes called "loaded antibodies," scientists combine them with chemo, radiation, or other drugs. The mAb finds the cancer cell, and the attached drug kills it.

  • Radiolabeled antibodies: Scientists attach a small radioactive particle to a mAb, which carries it to the cancer cell. For example, Ibritumomab tiuxetan (Zevalin) combines a mAb with a radioactive substance. It attacks a protein called CD20, found on certain cells in lymphoma (cancer of the lymph nodes).
  • Chemolabeled antibodies: For this type, scientists attach chemo or other types of drugs to various mAbs. For example, they bind a chemo drug called MMAE with a mAb to attack a protein linked to lymphoma.

Which Cancers Are Treated With mAbs?

Monoclonal antibodies work better on some types of cancer than others. And different mAbs treat different types of cancer. Some of the cancers that may be treated with mAbs are:

How You Get mAbs

Your doctor will inject the treatment or into a vein (IV). The length and number of treatments depend on the drug you're getting and the type of cancer you have.

You may get them along with other cancer treatments like chemo or hormone therapy.

Side Effects Of mAbs

You may have an allergic reaction where the needle goes into your skin or vein, though this often gets better over time. It could include:

  • Swelling
  • Itchiness
  • Soreness
  • Redness

Monoclonal antibodies can also cause flu-like symptoms like:

Talk to your doctor about rare but more serious side effects, especially in conjugated treatments that combine mAbs with chemotherapy or radiation. These could include:

WebMD Medical Reference

Sources

SOURCES:

American Cancer Society: "Monoclonal Antibodies and Their Side Effects," "Immune Checkpoint Inhibitors and Their Side Effects."

Cancer Research UK: "Monoclonal Antibodies (MABs)."

Mayo Clinic: "Monoclonal antibody drugs for cancer: How they work."

National Cancer Institute: "Monoclonal Antibodies."

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